#pragma once

#include <iostream>
#include <cstdio>
#include <string>
#include <fstream>
#include <sstream>
#include <mutex>
#include <memory>
#include <filesystem>   // c++17
#include <unistd.h>
#include <time.h>

namespace LogModule
{
    // 获取一下当前系统的时间
    std::string CurrentTime()
    {
        time_t time_stamp = ::time(nullptr);
        struct tm curr;
        localtime_r(&time_stamp, &curr);  // 时间戳，获取可读性较强的时间信息S

        char buffer[1024];
        // bug
        snprintf(buffer, sizeof(buffer), "%4d-%02d-%02d %02d:%02d:%02d", 
            curr.tm_year + 1900,
            curr.tm_mon + 1,
            curr.tm_mday,
            curr.tm_hour,
            curr.tm_min,
            curr.tm_sec
        );

        return buffer;
    }

    // 构成：1. 构建日志字符串 2. 刷新落盘(screen, file)
    // 1. 日志文件的默认路径和文件名
    const std::string defaultlogpath = "./log/";
    const std::string defaultlogname = "log.txt";

    // 2. 日志等级
    enum class LogLevel
    {
        DEBUG = 1,
        INFO,
        WARNING,
        ERROR,
        FATAL
    };

    std::string Level2String(LogLevel level)
    {
        switch(level)
        {
            case LogLevel::DEBUG:
                return "DEBUG";
            case LogLevel::INFO:
                return "INFO";
            case LogLevel::WARNING:
                return "WARNING";
            case LogLevel::ERROR:
                return "ERROR";
            case LogLevel::FATAL:
                return "FATAL";
            default:
                return "None";
        }
    }

    // 3. 刷新策略
    class LogStrategy
    {
    public:
        virtual ~LogStrategy() = default;
        virtual void SyncLog(const std::string &message) = 0;
    };

    // 3.1 控制台策略
    class ConsoleLogStrategy : public LogStrategy
    {
    public:
        ConsoleLogStrategy()
        {}
        ~ConsoleLogStrategy()
        {}
        void SyncLog(const std::string &message)
        {
            std::unique_lock<std::mutex> lock(_mutex);
            std::cout << message << std::endl;
        }
    private:
        std::mutex _mutex;
    };

    // 3.2 文件级（磁盘）策略
    class FileLogStrategy : public LogStrategy
    {
    public:
        FileLogStrategy(const std::string &logpath = defaultlogpath, const std::string &logname = defaultlogname)
            :_logpath(logpath)
            ,_logname(logname)
        {
            // 确认_logpath是存在的
            std::unique_lock<std::mutex> lock(_mutex);

            if(std::filesystem::exists(_logpath))
            {
                return ;
            }
            try
            {
                std::filesystem::create_directories(_logpath);
            }
            catch(const std::filesystem::filesystem_error& e)
            {
                std::cerr << e.what() << '\n';
            }      
        }

        ~FileLogStrategy()
        {}

        void SyncLog(const std::string &message)
        {
            std::unique_lock<std::mutex> lock(_mutex);

            std::string log = _logpath + _logname;  // ./log/log.txt
            std::ofstream out(log, std::ios::app);  // 日志写入，一定是追加
            if(!out.is_open())
            {
                return ;
            }
            out << message << '\n';
            out.close();
        }
    private:
        std::string _logpath;
        std::string _logname;

        std::mutex _mutex;
    };


    // 日志类：构建日志字符串，根据策略，进行刷新
    class Logger
    {
    public:
        Logger()
        {
            // 默认采用ConsoleLogStrategy策略
            _strategy = std::make_shared<ConsoleLogStrategy>();
        }

        void EnableConsoleLog()
        {
            _strategy = std::make_shared<ConsoleLogStrategy>();
        }

        void EnableFileLog()
        {
            _strategy = std::make_shared<FileLogStrategy>();
        }

        ~Logger()
        {}

        // 一条完整的信息：[2024-08-04 12:27:03] [DEBUG] [202938] [main.cc] [16] + 日志的可变部分(<< "hello world" << 3.14 << a << b;)
        class LogMessage
        {
        public:
            LogMessage(LogLevel level, const std::string &filename, int line, Logger &logger)
                :_currtime(CurrentTime())
                ,_level(level)
                ,_pid(::getpid())
                ,_filename(filename)
                ,_line(line)
                ,_logger(logger)
            {
                std::stringstream ssbuffer;
                ssbuffer << "[" << _currtime << "] " 
                         << "[" << Level2String(_level) << "] " 
                         << "[" << _pid << "] " 
                         << "[" << _filename << "] "
                         << "[" << _line << "] - ";
                _loginfo = ssbuffer.str();
            }

            template<typename T>
            LogMessage &operator << (const T &info)
            {
                std::stringstream ss;
                ss << info;
                _loginfo += ss.str();
                return *this;
            }

            ~LogMessage()
            {
                // 析构的时候打印内容
                if(_logger._strategy)
                {
                    _logger._strategy->SyncLog(_loginfo);
                }
            }

        private:
            std::string _currtime;      // 当前日志的时间
            LogLevel _level;            // 日志等级
            pid_t _pid;                 // 进程pid
            std::string _filename;      // 源文件名称??
            int _line;                  // 日志所在的行号
            Logger &_logger;            // 负责根据不同的策略进行刷新
            std::string _loginfo;       // 一条完整的日志记录
        };

        // 就是要拷贝
        LogMessage operator()(LogLevel level, const std::string &filename, int line)
        {
            return LogMessage(level, filename, line, *this);         // 优化成一次构造一次析构了 连续的构造 + 拷贝构造
        }
    private:
        std::shared_ptr<LogStrategy> _strategy;     // 日志刷新的策略方案
    };

    Logger logger;

#define LOG(Level) logger(Level, __FILE__, __LINE__)
#define ENABLE_CONSOLE_LOG() logger.EnableConsoleLog()
#define ENABLE_FILE_LOG() logger.EnableFileLog()
}